Active Site — Catalytic Site Vs

Understanding this difference allows you to ask the right questions: “Does this mutation abolish binding (active site defect) or just slow chemistry (catalytic site defect)?” – a distinction that can mean the difference between a non-functional enzyme and one with altered specificity.

| Feature | Active Site | Catalytic Site | |---------|-------------|----------------| | | Entire functional region | Subset of active site | | Primary role | Substrate binding, orientation, microenvironment | Bond making/breaking | | Residues involved | Many (often 10-20+ contact points) | Few (2-6 chemically reactive residues) | | Mutation effect | Loss of binding or specificity | Loss of catalytic rate (Vmax ↓), but binding (Km) may remain | | Detected by | Substrate analog binding, X-ray crystallography | Transition-state analog binding, pH-rate profiles, isotope effects | | Examples | All enzymes | Ribozymes, proteases, kinases, lysozyme (Glu35 & Asp52) | catalytic site vs active site